1. Field of the Invention
The present invention relates to an optical disk apparatus, a method of recording on an optical disk, and an optical disk, and may be applied, for example, to a minidisk (MD), a compact disk (CD), a digital video disk (DVD), etc., and recording and playback apparatuses therefor. More specifically, according to the present invention, bit sequences of information regarding copyright are respectively scrambled using different binary sequences to generate plural lines of signals, and the plural lines of signals are further scrambled to generate a single line of drive signal, with which laser beam is modulated, so that the benefits of the copyright holder are protected more effectively compared with before.
2. Description of the Related Art
Minidisk apparatuses, which are a type of optical disk apparatuses, have been rapidly spreading in recent years because they readily allow copying of various contents of music while not degrading the quality of sound. More specifically, the minidisk apparatuses allow music information distributed via the Internet to be recorded on minidisks for audition, and also allow music on a compact disk borrowed from a friend, etc. to be recorded on a minidisk for audition. Furthermore, music can also be copied from minidisk to minidisk.
Although the easy copying of music, with the sound quality maintained, provides considerable advantages to the user, the benefits of the copyright holder who has created the music may be impoverished. Thus, in organizations and forums such as RIAA (Recording Industry Association of America), SDMI (Secure Digital Music Initiative), CPTWG (Copy Protection Technical Working Group), various approaches have been considered aiming at protection of the benefits of the copyright holder.
As one of the approaches, a method has been proposed in which music information is recorded while being encrypted using copyright protection information which is unique to each storage medium. According to this method, if the music information is copied to another storage medium, decryption is inhibited because the copyright protection information differs from storage medium to storage medium. Accordingly, unrestricted copying of the music information is prevented, thereby protecting the benefits of the copyright holder.
As methods of recording the copyright protection information, for example, a method in which a sector inhibited from user access is provided and the copyright protection information is recorded in the sector, and a method in which a reflection film is partially removed from recording of primary data in the form of a pit sequence so that the copyright protection information is recorded in the form of bar codes (International Publication No. WO97/14144), have been proposed.
These methods, however, are not still practically sufficient to effectively protect the benefits of the copyright holder.
More specifically, in accordance with the method in which the copyright protection information is recorded in the sector inhibited from user access, while the copyright protection information can be recorded relatively easily, the copyright protection information is rather susceptible to copying.
In accordance with the method in which the copyright protection information is recorded in the form of bar codes by partially removing the reflection film, recording of the copyright protection information can be visually checked by observations using a microscope, etc., for the purpose of copying. Thus, so-called pirated editions cannot be fully prevented. Instead of removing the reflection film, in another method, an opaque film may be partially formed on the surface of an optical disk, the copyright protection information being recorded in a similar manner. However, this method also suffers the similar problem as in the method in which the reflection film is partially removed.
The present invention has been made in view of the above, and an object thereof is to provide an optical disk apparatus, a method of recording on an optical disk, and an optical disk which serve to protect the benefits of the copyright holder more effectively compared with before.
To this end, the present invention, in one aspect thereof, provides an optical disk apparatus which records information regarding copyright on a disk-shaped storage medium by emission of laser beam. The optical disk apparatus includes a plurality of binary sequence generating units for generating binary sequences corresponding to the number of bits of the information regarding copyright, at a transmission rate which is faster than that of the information regarding copyright; a plurality of operation units for operating the binary sequences with corresponding bits of the information regarding copyright and outputting a plurality of operation results; a selection unit for outputting a drive signal by selectively outputting, according to a predetermined switching signal, the plurality of operation results; and a modulation unit for modulating the laser beam in accordance with said drive signal.
Thus, the bits of the information regarding copyright are scrambled with one another, and also scrambled using the binary sequences. Accordingly, the information regarding copyright is inhibited from detection; thus, the benefits of the copyright holder can be protected more effectively compared with before.
The present invention, in another aspect thereof, provides a method of recording on an optical disk, in which information regarding copyright is recorded on a disk-shaped storage medium by emission of laser beam. The method includes the steps of generating plural lines of signals by respectively scrambling bit sequences of the information regarding copyright with different binary sequences having a transmission rate which is faster than that of the information regarding copyright; scrambling the plural lines of signals to generate a single line of drive signal; and modulating the laser beam in accordance with the single line of drive signal.
Thus, the bits of the information regarding copyright are scrambled with one another, and also scrambled using the binary sequences. Accordingly, the information regarding copyright is inhibited from detection; thus, the benefits of the copyright holder can be protected more effectively compared with before.
The present invention, in another aspect thereof, provides an optical disk on which information regarding copyright is recorded. In the optical disk, each bit of the information regarding copyright is recorded while being distributed in the circumferential direction of an information recording surface of the optical disk.
Accordingly, the information regarding copyright is inhibited from detection; thus, the benefits of the copyright holder can be protected more effectively compared with before.
The present invention, in another aspect thereof, provides an optical disk apparatus, in which encryption processing is performed using information regarding copyright which is recorded on an optical disk. The optical disk apparatus includes a playback signal generating unit for emitting laser beam on the optical disk, receiving returning light, and generating a playback signal in accordance with the returning light; a binary sequence generating unit for generating a plurality of binary sequences with reference to a synchronization pattern of the playback signal; a plurality of sampling units for sampling the playback signal with reference respectively to the binary sequences to thereby output a plurality of sampling results; a plurality of integration units for respectively integrating the plurality of sampling results to thereby output a plurality of integration results; and a determination unit for respectively determining the integration results and decoding corresponding bit sequences of the information regarding copyright.
Accordingly, even if the bits of the copyright protection information is scrambled with one another and also scrambled using the binary sequences so as to inhibit detection, the information regarding copyright can be accurately played back.
In accordance with the present invention, bit sequences of information regarding copyright are respectively scrambled using different binary sequences to generate plural lines of signals, and the plural lines of signals are further scrambled to generate a single line of drive signal, with which laser beam is modulated. Accordingly, the benefits of the copyright holder can be protected more effectively compared with before.